The present invention relates to a method, in a roller printing unit, of locking the rollers in associated bearing housings in connection with movement of the rollers from open position to working position. The present invention also relates to a locking apparatus for rollers in a printing unit of the type in which a number of cooperating rollers suspended in a frame are movable between a working position and an open position in which the rollers are located a distance from one another and from their associated bearing housings.
Printing units for printing web-shaped material, e.g. packaging material, are normally of the roller type, i.e. they use rollers to transfer printing ink in the desired pattern from an ink reservoir to a material web running through the printing unit. In such instance, the printing unit includes a plurality of rollers, e.g. a counterpressure roller, over which the material web runs, a stereo roller or cylinder in abutment against the counterpressure roller and whose surface displays the desired printing pattern, and an anilox (or inking) roller which is in abutment against the stereo roller and which transfers the desired quantity of ink from an ink reservoir to the stereo roller. In the working position of the printing unit, the various rollers abut against one another (but the material web runs, however, between the counterpressure roller and the stereo roller), while the rollers are separated from one another when the printing unit is in the open position, and are located a distance from one another. This allows for the replacement of the stereo roller or replacement of a part of the stereo roller, e.g. a sleeve carrying the desired artwork pattern. Naturally, the open position of the printing unit allows replacement of the remaining rollers, as well as infeed of the material web in the correct position before the printing unit is closed, i.e. the rollers are brought to the previously described working position in order, when the printing unit is in operation, progressively to transfer ink from a printing ink reservoir and to the material web passing through the unit. It is of major importance that the maneuvering of the printing unit between the open and closed positions can take place in a rapid and smooth manner, since it is often necessary to replace the stereo roller carrying the artwork or a part of the roller at relatively short intervals. A rapid and reliable replacement of the rollers is also naturally of major importance.
In prior art types of roller printing units, the stereo and anilox rollers are normally displaced between closed and open position along a linear guide (often extending more or less vertically). In such instance, the rollers are carried by bearing housings which are movable along the linear guide. In order to make for replacement of the rollers, the bearing housings have a removable, upper section which functions as a locking device, which may either be connected to the rest of the bearing housing by means of mechanical unions, such as screws or bolts, and hereby be removed entirely manually, or may be movable hydraulically or pneumatically. In the first-mentioned case, replacement of, for example, a stereo roller requires the manual dismounting of the upper sections or locking devices of the bearing housings (or alternatively the whole bearing housing), replacement of the roller, and also manual remounting and alignment. A more rapid replacement is made possible in the above-mentioned hydraulic or pneumatic constructions in which the locking device may be removed automatically during the movement of the rollers and bearing housings to the open position, and be re-activated when the rollers are moved, after replacement of, for example, the stereo roller, in a direction towards the closed position or working position in which the rollers once again abut against one another. However, hydraulic or pneumatic constructions are relatively bulky and it has also proved in practice that this type of construction not always operates with the desired reliability and precision.
There is thus a general need in the art to realize, in roller printing units, a method of locking the rollers in associated bearing housings, the method not suffering from the above-outlined drawbacks but making for rapid and simple locking and release, respectively, in connection with movement of the rollers of the printing unit between the open and closed position.
One object of the present invention is to realize a method, in a roller printing unit, of locking the rollers in associated bearing housings in connection with the movement of the rollers from the open position to the working position, the method being automatic and totally synchronized with the movement of the rollers.
A further object of the present invention is to realize a method of the type disclosed by way of introduction, the method affording reliable function and also making it possible to obviate the shortcomings in reliability and precision inherent in prior art methods.
The above and other objects have been attained according to the present invention in that a method of the type described by way of introduction has been given the characterizing feature that the movement of the rollers in relation to the frame of the printing unit is mechanically transferred to and maneuvers locking devices at the bearing housings of the rollers between open and closed position.
Preferred embodiments of the method according to the present invention have further been given the characterizing features as set forth in appended subclaims 2 to 4.
There is further a general need in the art to realize an automatic locking apparatus for rollers in a printing unit, the locking apparatus being of simple and economical design and construction which may readily be adapted to and employed in printing units of the customary major types.
One object of the present invention is thus to realize a locking apparatus for rollers in a printing unit of the type in which cooperating rollers are movable between a working position and an open position, the locking apparatus being of simple construction and requiring neither manual labor inputs nor complicated hydraulic or pneumatic drive means.
A further object of the present invention is to realize a locking apparatus of the above-mentioned type, the locking apparatus permitting, on the one hand, reliable locking of the stub shafts of the rollers in associated bearing housings, and, on the other hand, good accessibility when the rollers are to be replaced and the locking apparatus is located in its open position.
Yet a further object of the present invention is to realize a locking apparatus of the type described by way of introduction, the locking apparatus being of a construction which permits a totally automated function independently of either manual labor inputs or separate drive means of, for example, the pneumatic, hydraulic or electric type.
Still a further object of the present invention is, finally, to realize a locking apparatus of the above-mentioned type which does not suffer from the drawbacks inherent in previously mentioned apparatuses.
The above and other objects have been attained according to the present invention in that a locking apparatus of the type described by way of introduction has been given the characterizing features that the bearing housings include locking devices for the rollers, the locking devices being disposed to cooperate with maneuvering devices mounted on the frame such that, in the working position of the rollers, they are located in a closed position, and in the open position of the rollers are located in an open position.
Preferred embodiments of the apparatus according to the present invention have further been given the characterizing features as set forth in appended subclaims 6 to 9.